Hello All - during my new boat search I was trying to decide between the Imor 5.7 or 6.0 and a well respected MasterCraft dealer (by most of us on ths forum) sent this email below regarding an independent study on "true HP" for the top 3 motor companies. (see the attachement) I found it very interesting and if this is something you've already seen sorry for the re-post!
ENJOY:

Hey Paul

Most Manufacturers overstate their HP dramatically, as you can see below from the CARB testing the true HP of each engine. That PCM your buddy has is really only 360HP, not 409 as they advertise. The horsepower of the Ilmor 5.7 is 320 vs 277 in PCM. All of our staff can see a dramatic difference in the performance of the ilmor vs indmar. Unfortunately, we are usually focuses on torque with extra ballast, not top end.

One of my employees is a big barefooter, and I was asking him about it. He said that with your size the Illmor would be really close to getting your 44MPH, but couldn’t guarantee it. He did mention that all footers are using the 5.7 and he doesn’t even know anyone with 6.0 Ilmor in MC. He said some will get the tower also, which helps with the start and reduces drag at top end, because it is pulling up. I checked with my rep and he said everyone he knows foots with 5.7 in Ilmor.